When should you prune hydrangeas?
You might expect to prune Hydrangeas immediately after they flower (in autumn), but that's not the case! Advice is to simply leave the spent flowers on your Hydrangea over winter and only prune them in the spring, after the chance of severe frost has passed. The flowers protect the new flower buds from frost by insulating them. Moreover, you can enjoy the flowers for longer if you leave them in place - even when dried or covered in snow and frost, Hydrangea flowers are a spectacle to behold.
Hydrangeas: new/annual wood or old wood?
Exactly how to prune a Hydrangea depends on the variety. Does your variety flower on new or annual wood, or on old wood (also called biennial wood)?
Old wood-flowering Hydrangeas
Most Hydrangeas flower on old wood, meaning they flower on top of the flower buds formed the year before. Types of Hydrangeas that flower on old wood include:
- Hydrangea macrophylla (Farmers' Hydrangea): this 'common Hydrangea' is known for its large flower heads and is available in different colours such as purple, pink, blue and white.
- Hydrangea quercifolia (Oakleaf Hydrangea): this species has oak-leaf-like leaves with cone-shaped, white flower clusters.
- Hydrangea involucrata (Ball hydrangea): the flower buds of this small, umbelliferous species are cone-shaped before they open.
New/annual wood-flowering Hydrangeas
Some Hydrangeas flower on annual wood, meaning they flower on the branches that have grown in that same year. Hydrangea species that flower on annual wood include:
- Hydrangea paniculata (Plume Hydrangea): plume hydrangeas can be recognised by the white flowers that bloom like plumes. They flower on both old and new wood, but in terms of pruning, base this species on annual wood.
- Hydrangea arborescens (bulbous Hydrangea): these Hydrangeas often produce white flowers, such as the popular ‘Annabelle’ Hydrangea.
Hydrangea pruning: how do you do it?
How do you prune a Hydrangea? We'll explain it to you below. Make sure to confirm what type of Hydrangea you have, as we explain above.
How to prune Hydrangeas that flower on new/annual wood
Preferably, you should prune Hydrangeas that flower on annual wood, such as Plum Hydrangea and Ball Hydrangea, in the early spring (late February/March). Prune before new growth starts and when the chance of severe frost has passed, to avoid frost damage to pruning wounds. Prune all the branches of your Hydrangeas to about 15 centimetres above the ground. This encourages the growth of new shoots and ensures rich flowering in the coming season.
How to prune Hydrangeas that flower on old wood
Pruning old wood-flowering Hydrangeas, such as the Peasant Hydrangea, isn't necessary. The flower buds will have already formed on the previous year's branches, so you should prune only if you want to contain or rejuvenate the plant. Pruning these Hydrangeas needs to be much less drastic than with Hydrangeas that flower on annual wood. You have several choices:
- Don't need to limit growth and rejuvenate your Hydrangea? Choose to remove only the spent flowers, in early spring.
- Are there damaged or weak branches? Prune those branches back in early spring and leave the healthy branches alone.
- Do you want to limit the growth of your Hydrangea? Prune back a third to half of the Hydrangea to about 30 centimetres above the ground in the early spring. For example, you can shorten the longest and weakest/oldest branches, but don't prune them back too close to the ground. Don't prune more than necessary - it's better to do too less than too much, as this variety of Hydrangea needs older branches to flower thickly.
Everything you need to know about Hydrangeas: caretaking, flowering, symbolism and origins
By understanding how Hydrangeas bloom and what kind of pruning is needed, you'll take the best possible care of the plant and enjoy beautifully flowering Hydrangeas year after year. Want to know more about Hydrangeas, such as caretaking tips and the symbolism and origins of the plant? Take a look at our comprehensive guide to Hydrangeas, with extensive information on the Hydrangea as a garden plant and cut flower.
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